The intensive use of molecular markers has already modified and even revolutionized certain areas of biology over the last ten years. This book makes an overall survey of molecular markers in formal genetics, population genetics, quantitative genetics and molecular biology. It defines concepts, explains techniques and provides the bibliographic references necessary to understand and use this now essential tool. This comprehensive study focuses on plants. Nevertheless, since most of the tools and concepts are common to all organisms containing DNA, any biologist concerned with markers will read this book with great interest, regardless of his field of research.